JP2011137418A - Catalyst converter holding material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a holding material with a protecting film formed thereon, having less reduced initial holding force and improved winding work efficiency on a catalyst carrier while maintaining the original reinforcing effect of the protecting film and the friction resistance reducing effect thereof when pressed in. <P>SOLUTION: This catalyst converter holding material is used for a catalyst converter which includes the catalyst carrier, a metal casing storing the catalyst carrier, and the holding material wound on the catalyst carrier and mounted in a clearance between the catalyst carrier and the metal casing. The catalyst converter holding material includes the protecting film having openings and bonded to the surface of an inorganic fiber substrate at the side of the metal casing. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention provides a catalyst carrier incorporated in a catalytic converter for removing particulates, carbon monoxide, hydrocarbons, nitrogen oxides and the like contained in exhaust gas discharged from an internal combustion engine such as a gasoline engine or a diesel engine. The present invention relates to a holding material for a catalytic converter (hereinafter also simply referred to as “holding material”) for holding in a casing.

  As is well known, vehicles such as automobiles are equipped with a catalytic converter for exhaust gas purification in order to remove harmful components such as carbon monoxide, hydrocarbons and nitrogen oxides contained in the exhaust gas of the engine. Yes. FIG. 7 is a cross-sectional view schematically showing an example of a catalytic converter. In this catalytic converter 10, an introduction pipe 16 into which exhaust gas discharged from an internal combustion engine is introduced is connected to one end portion of a metal casing 11, and exhaust gas that has passed through the catalyst carrier 12 is connected to the other end portion. A discharge pipe 17 for discharging to the outside is provided. Further, inside the metal casing 11, a catalyst carrier 12 is installed via a holding material 13.

  Since the catalyst carrier 12 is generally a cylindrical honeycomb-shaped body made of, for example, cordierite or the like, a noble metal catalyst or the like is supported on the holding material 13. A function of safely holding the catalyst carrier 12 so that the metal carrier 12 does not collide with the metal casing 11 and is damaged, and a function of sealing so that unpurified exhaust gas does not leak from the gap between the catalyst carrier 12 and the metal casing 11. It is necessary to combine these functions. Therefore, currently, inorganic fibers such as alumina fibers, mullite fibers, or other ceramic fibers are formed into a mat having a predetermined thickness using an organic binder. Moreover, the shape has shown the planar shape shown to FIG. 8 (A), the convex part 42 is formed in the end of the flat plate-shaped main-body part 41, and the convex part 42 can be fitted in the other end. A concave portion 43 having an arbitrary shape is formed. Then, as shown in FIG. 8B, the main body 41 is wound around the outer peripheral surface of the catalyst carrier 12, and the convex portion 42 and the concave portion 43 are engaged to be wound around the catalyst carrier 12.

  As the organic binder, rubbers, water-soluble organic polymer compounds, thermoplastic resins, thermosetting resins and the like are common. Further, if the holding material 13 is too thick, it is difficult to wind the catalyst carrier 12 and mount it on the metal casing 11, so it is necessary to reduce the thickness to some extent. For this reason, in the general holding material 13, these organic binders are used in an amount of 5 to 8% by mass of the total amount of the holding material, and in most cases about 10% by mass.

However, recently, in order to increase the purification efficiency, the catalyst carrier 12 is heated to close to 1000 ° C., so that the organic binder listed above is easily decomposed and burned off, and CO ₂ , CO, and various organic gases are In particular, a large amount is generated early in the operation of the catalytic converter. The exhaust gas regulations are becoming stricter, and there is a possibility of exceeding the specified value due to CO ₂ derived from the organic binder. Further, recently, electronic control of the engine has been advanced. However, if there is CO ₂ unrelated to the original exhaust gas, the exhaust system sensors are erroneously operated to adversely affect the electronic control of the engine. In order to prevent such problems, manufacturers are working to burn organic binders by firing before shipping.

  It is also considered to reduce the amount of the organic binder used, but there is a problem that the binding force of the inorganic fibers is weakened by the reduced amount, the holding material 13 becomes thick, and the assembling property is deteriorated. In addition, due to the decrease in the organic binder, problems such as a decrease in strength on the casing-side surface of the holding material 13 and an increase in the friction coefficient may be considered. Recently, in the production of a catalytic converter, it has become the mainstream to press-fit a catalyst carrier 12 wound with a holding material 13 into a cylindrical metal casing 11, and a film or tape is applied to the casing-side surface of the holding material 13. A protective film 50 such as a nonwoven fabric or a resin coating layer is formed to reduce frictional resistance during press-fitting and to reinforce the casing side surface (see Patent Documents 1 and 2).

JP 2001-32710 A JP-A-8-61054

  Since the holding material 13 on which such a protective film 50 is formed has a low frictional resistance of the protective film itself, it is excellent in canning property and is expected to improve production efficiency. However, during the winding work around the catalyst carrier 12, the length of the outer circumference on which the protective film is formed becomes larger than the inner circumference in contact with the catalyst carrier, that is, the outer circumference is pulled. There is concern about tearing or partial peeling.

  The present invention has been made in view of such a situation, and in a holding material on which a protective film is formed, a protective film is formed by making a hole in the protective film 50 to impart (control) stretchability to the protective film. It aims at improving the winding workability | operativity to a catalyst support | carrier, maintaining the effect of reducing the frictional resistance at the time of press fit, and the friction resistance at the time of press fit.

In order to achieve the above object, the present invention provides the following holding material for a catalytic converter.
(1) Holding used for a catalytic converter comprising a catalyst carrier, a metal casing that houses the catalyst carrier, and a holding member that is wound around the catalyst carrier and interposed in a gap between the catalyst carrier and the metal casing. Material,
A holding material for a catalytic converter, wherein a protective film having an opening is bonded to a surface of an inorganic fiber substrate on a metal casing side.
(2) The holding material for a catalytic converter according to the above (1), wherein the opening ratio in the protective film is 10 to 45%.
(3) The holding material for a catalytic converter according to the above (1) or (2), wherein the shape of the opening is a circle or an ellipse.
(4) The holding material for a catalytic converter as described in any one of (1) to (3) above, wherein the minimum length of the opening is 5 mm or more.
(5) The holding material for a catalytic converter according to any one of (1) to (4) above, wherein an interval between adjacent openings is 3 mm or more.
(6) The basis weight of the protective film in which the opening is formed is 20 g / m ² or less, wherein the holding material for a catalytic converter according to any one of (1) to (5) above .
(7) The holding material for a catalytic converter according to any one of (1) to (6) above, wherein the organic component of the whole holding material is 3% by mass or less of the total amount of the holding material.

  Since the holding material of the present invention has an opening formed in the protective film, the difference in area between the state wound around the catalyst carrier and the state where the protective film is heated and burned off before shipping is small. The overall flexibility is also improved, and the workability on the catalyst carrier is also improved. Accordingly, it is possible to improve the workability of winding around the catalyst carrier while maintaining the original reinforcing effect of the protective film and the effect of reducing the frictional resistance during press-fitting. Furthermore, the amount of organic components generated when the protective film is burned down is reduced, the burning work prior to shipment of the catalytic converter can be completed in a short time, and the exhaust equipment can be reduced in scale.

(A) The top view which shows the holding | maintenance material for catalytic converters of this invention, (B) The perspective view which shows the state wound around the catalyst support | carrier. It is a top view which shows the other example of an opening pattern. It is a top view which shows the other example of an opening pattern. It is a top view which shows the other example of an opening pattern. It is a top view which shows the other example of an opening pattern. It is a top view which shows the holding material used in the Example. It is sectional drawing which shows an example of a catalytic converter. (A) The top view of the conventional holding | maintenance material for catalytic converters, (B) It is a perspective view which shows the state wound around the catalyst support | carrier.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an example of the holding member 13 according to the present invention, in which (A) is a plan view corresponding to FIG. 8 (A), and (B) is a perspective view corresponding to FIG. 8 (B). FIG. As shown in the figure, a protective film 50A is bonded to the casing-side surface of the inorganic fiber substrate 45, and a large number of circular openings 60 are formed over the entire surface of the protective film 50A.

  The formation pattern of the openings 60 may be formed at regular intervals as shown in FIG. 1, or may be formed in a staggered pattern as shown in FIG. Moreover, although illustration is abbreviate | omitted, you may form at random. Furthermore, as shown in FIG. 3, circles having different sizes may be combined.

  In addition to the circular shape, the opening 60 may be elliptical as shown in FIG. The major axis of the ellipse may be formed along the longitudinal direction (left and right direction on the paper surface) of the holding member 13 as illustrated, or may be formed to be orthogonal to the longitudinal direction (up and down direction on the paper surface). However, it may be formed along the diagonal direction in the longitudinal direction. Since the holding member 13 is press-fitted in the width direction, the holding member 13 is easily press-fitted by forming the opening 60 so that the major axis coincides with the width direction of the holding member 13. On the other hand, by forming the opening 60 so that the major axis of the ellipse coincides with the longitudinal direction of the holding material 13, it becomes easy to bend when wound around the catalyst carrier 12. Further, as shown in the figure, ellipses having different sizes may be combined. As shown in Test 1 to be described later, the elliptical opening also has an advantage that it has a higher tensile strength than the circular opening.

  Further, it is preferable that the opening 60 has a minimum length, that is, a diameter in the case of a circle as shown in FIGS. 1 to 3 and a minor axis of 5 mm or more in the case of an ellipse as shown in FIG. 10 to 15 mm is more preferable. When the openings 60 having different sizes are mixed as shown in FIGS. 3 and 4, the diameter or the short axis of the smallest opening is set to 10 mm or more. Since the periphery of the opening 60 becomes resistance during press-fitting, the smaller the opening diameter, the more openings 60 must be formed, and the frictional resistance during press-fitting increases. On the other hand, if the opening diameter exceeds 30 mm, a large amount of the base material 45 is exposed and the frictional resistance during press-fitting increases.

  The interval D between the adjacent openings 60 is preferably 3 mm or more, and more preferably greater than 5 mm and 15 mm or less. Since the protective film 50A between the openings becomes narrower as the interval between the adjacent openings 60 becomes narrower, the protective film 50A is likely to break during press-fitting. Further, since the protective film 50A between the openings becomes wider as the interval between the openings 60 becomes wider, the breakage of the protective film 50A at the time of press-fitting can be suppressed, but the effect of providing the openings 60 decreases.

  Furthermore, as shown in FIG. 5, it is preferable not to form the opening 60 in the peripheral region 47 of the convex portion 42 of the main body 41 of the holding member 13 and the peripheral region 48 of the concave portion 43. As shown in FIG. 1B, the convex portion 42 and the concave portion 43 are portions that are engaged when the holding material 13 is wound around the catalyst carrier 12. It may get caught on the inner surface of the casing. Even if there is a step at the engagement end edge, the frictional resistance is reduced by the protective film 50A and it is easy to press-fit, but if the opening 60 is present, the base material 45 is exposed and the frictional resistance is increased accordingly. Therefore, by not forming the opening 60 only in the peripheral portions 47 and 48 of the convex portion 42 and the concave portion 43, the frictional resistance can be reduced as much as possible. Therefore, as the peripheral portions 47 and 48 become wider, the frictional resistance at the time of press-fitting can be reduced. However, since the effect of providing the opening 60 decreases, the width of the peripheral portions 47 and 48 is the dimension in the figure. It is preferable that a is 50 to 100% of the full width of the holding material, b is 5 to 9% of the full length of the holding material, c is 5 to 9% of the full length of the holding material, and d is 50 to 100% of the full width of the holding material.

  In any of the above-described forms of forming the opening 60, the opening ratio of the opening 60, that is, the ratio of the opening 60 in the total area of the protective film 50A is preferably 10 to 45%, and 20 to 35%. It is more preferable that As the aperture ratio decreases, the effect of providing the opening 60 decreases although the decrease in the original function of the protective film is small. On the other hand, the larger the aperture ratio, the greater the decrease in the original function of the protective film. Further, the base material 45 is exposed, and the frictional resistance increases accordingly, resulting in poor canning performance. Therefore, the aperture ratio range is set by adjusting the size of the openings 60, the interval between the apertures, the combination of apertures having different sizes, the formation pattern, and the like.

  The material of the protective film 50A may be a conventionally known material. For example, polyethylene, ethylene-vinyl acetate copolymer, polypropylene, polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, polyamide, polystyrene, polycarbonate, polyethylene terephthalate, poly Examples include films and non-woven fabrics made of butylene terephthalate. In the present invention, an organic non-woven fabric such as a non-woven fabric made of polyethylene resin, which is available at low cost and is easy to punch, can be suitably used.

The thickness of the protective film 50A is not limited. However, if the thickness is too thin, the film strength becomes low, and the film tends to be broken after being wound around the catalyst carrier 12 or when it is press-fitted. Further, if it becomes too thick, it will be difficult to stretch, it will be difficult to wind it around the outer peripheral surface of the catalyst carrier 12, and the organic component will increase, and the total amount with the base material 45 will be suppressed to 3% by mass or less as will be described later. Becomes difficult. The film strength is preferably 0.5 N / 30 mm or more in terms of tensile strength, and more preferably 2 N / 30 mm or more. The tensile strength is measured according to JIS P 8813. Such tension satisfies the strength, in order to suppress the organic component is preferably set to 20 g / ^{m 2} or less in basis weight after ^opening, 2 to 10 g / m 2, to a 2-5 g / ^{m 2} Is more preferable.

  In the case of an organic non-woven fabric, the fibers may be present randomly on the surface, but in the circumferential direction when wound around the outer peripheral surface of the catalyst carrier 12 by being oriented in the longitudinal direction of the holding material 13. It becomes easy to stretch and wearability improves. In addition, when oriented in the width direction, the film strength in the press-fitting direction increases.

  In order to join the protective film 50A to the base material 45, a film or a non-woven fabric in which the opening 60 is formed can be used by using an adhesive or by hot pressing. However, the method using an adhesive increases the organic content, and in the case where the adhesive is a non-woven fabric, the adhesive tends to protrude from the gap between the fibers, resulting in poor appearance.

  The base material 45 is not limited. For example, the base material 45 is made of a blanket obtained by wet-molding inorganic fibers and a small amount of an organic binder and then drying in a compressed state, and a needle-processed collection of inorganic fibers. A mat material such as an expansion mat obtained by wet molding a mat, an inorganic fiber, and an expansion material such as vermiculite can be used.

  Further, the overall shape is not limited. For example, as shown in FIG. 1A, a convex portion 42 is formed at one end of a flat plate-like main body portion 41, and the convex portion 42 can be fitted to the other end. It can be made the shape which formed the recessed part 43 of this. In addition, the shape of the convex part 42 and the recessed part 43 may be a triangle and a semicircle shape other than the rectangle shown in figure. Further, the number of the convex portions 42 and the concave portions 43 is not limited to one, and may be two or more.

As the inorganic fiber, various inorganic fibers conventionally used for holding materials can be used. For example, alumina fibers, mullite fibers, or other ceramic fibers can be used as appropriate. More specifically, as the alumina fiber, for example, Al ₂ O ₃ is preferably 90% by weight or more (the remainder is SiO ₂ minutes), and X-ray is preferably low crystallinity, An average fiber diameter of 3 to 10 μm and a wet volume of 300 cc / 5 g or more are preferable. As the mullite fiber, for example, a mullite composition having an Al ₂ O ₃ minute / SiO ₂ minute weight ratio of about 70/30 to 83/17 and having a low crystallinity in terms of X-ray is preferable. The average fiber diameter is preferably 3 to 10 μm and the wet volume is 300 cc / 5 g. Examples of other ceramic fibers include silica-alumina fibers, any of which may be conventionally used for holding materials. Moreover, you may mix | blend glass fiber, a silica fiber, rock wool, and biosoluble inorganic fiber.

The wet volume is calculated by the following method.
1) Weigh 5 g of dried fiber material with a scale having an accuracy of two decimal places or more.
2) Place the weighed fiber material into a 500 g glass beaker.
3) About 400 cc of distilled water having a temperature of 20 to 25 ° C. is placed in the glass beaker of 2), and carefully stirred and dispersed using a stirrer so as not to cut the fiber material. An ultrasonic cleaner may be used for this dispersion.
4) Transfer the contents of the glass beaker of 3) to a 1000 ml graduated cylinder and add distilled water to a scale of 1000 cc.
5) Close the mouth of the graduated cylinder of 4) with your hands, and stir it upside down, taking care not to leak water. This is repeated a total of 10 times.
6) After the stirring is stopped, the mixture is allowed to stand at room temperature, and the fiber sedimentation volume after 30 minutes is visually measured.
7) The above operation is performed on three samples, and the average value is taken as the measured value.

  The organic binder may be a known one, and rubbers, water-soluble organic polymer compounds, thermoplastic resins, thermosetting resins, and the like can be used. Specifically, examples of rubbers include a copolymer of n-butyl acrylate and acrylonitrile, a copolymer of ethyl acrylate and acrylonitrile, a copolymer of butadiene and acrylonitrile, and butadiene rubber. Examples of the water-soluble organic polymer compound include carboxymethyl cellulose and polyvinyl alcohol. Examples of thermoplastic resins include homopolymers and copolymers such as acrylic acid, acrylic ester, acrylamide, acrylonitrile, methacrylic acid, methacrylic ester, acrylonitrile / styrene copolymer, acrylonitrile / butadiene / styrene copolymer Etc. Examples of the thermosetting resin include a bisphenol type epoxy resin and a novolac type epoxy resin.

  Moreover, it is also possible to mix | blend a small amount of organic fibers, such as a pulp, with the base material 45 as an organic binder. The thinner and longer the organic fiber, the higher the binding force, and highly fibrillated cellulose and cellulose nanofiber are preferred. Specifically, the fiber diameter is preferably 0.01 to 50 μm, the fiber length is preferably 1 to 5000 μm, the fiber diameter is preferably 0.02 to 1 μm, and the fiber length is more preferably 10 to 1000 μm.

  These organic binders can be used in combination of two or more. Although there will be no restriction | limiting if the usage-amount of an organic binder is the quantity which can bind an inorganic fiber, It is 0.1-10 mass parts with respect to 100 mass parts of inorganic fibers. When the organic binder is less than 0.1 parts by mass, the binding force is insufficient, and when it exceeds 10 parts by mass, there is a possibility that the exhaust gas regulations may be exceeded when disappearing. A preferable amount of the organic organic binder is 0.2 to 6 parts by mass, and a more preferable amount is 0.2 to 3 parts by mass.

  An organic binder and an inorganic binder may be used in combination. According to the combined use of the organic binder and the inorganic binder, in order to avoid the above-mentioned problems caused by the volatilization of the organic component at the time of use, the inorganic fibers are bound well even when the amount of the organic binder used is reduced. In addition, it is possible to provide a holding material for a catalytic converter that can maintain the same thickness as the conventional one. Such inorganic binders may be known ones, and examples thereof include glass frit, colloidal silica, alumina sol, sodium silicate, titania sol, lithium silicate, water glass, and bentonite. In addition, these inorganic binders can also be used in combination of 2 or more types. Although the usage-amount of an inorganic binder will not be restrict | limited if it is the quantity which can bind an inorganic fiber, it is 0.1-10 mass parts with respect to 100 mass parts of inorganic fibers. If the inorganic binder is less than 0.1 parts by mass, the binding force is insufficient, and if it exceeds 5 parts by mass, the amount of inorganic fibers is relatively reduced, and the holding performance and sealing performance required as a holding material cannot be obtained. A preferable amount of the inorganic binder is 0.2 to 6 parts by mass, and a more preferable amount is 0.2 to less than 4 parts by mass.

  The smaller the total organic content of the holding material, that is, the total of the base material 45 and the protective film 50A, the better. Specifically, the organic content is preferably 3% by mass or less, more preferably 2% by mass or less, particularly preferably 1.5% by mass or less, 1.0% by mass or less, 0.5% or less of the total amount of the holding material. It can also be made into the mass% or less. Therefore, in the base material 45, it is preferable to keep the organic binder and the organic fiber in a very small amount so that the compressed state can be maintained.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited at all by this.

(Test 1)
As shown in Table 1, a circular or elliptical opening was formed in a polyethylene nonwoven fabric having a basis weight of 5 g / m ² and a width of 70 mm by drilling to obtain a test piece. The openings were arranged in three rows in the width direction, and the number in the longitudinal direction was the same. Further, the distance from the end face to the opening is the dimension b in FIG. And the test piece was mounted | worn with the tension test machine based on JISP8113, and the elongation amount of the nonwoven fabric until it reached the maximum point load (load leading to a fracture | rupture) and the tensile load of 7N was measured at the tensile speed of 10 mm / min. The results are shown in Table 1, but are shown as relative values with a polyethylene nonwoven fabric (test number 6) that does not form openings as 100. The results are also shown in Table 1. It can be said that the elliptical opening has a higher tensile strength than the circular opening, and has a higher effect of suppressing breakage of the protective film when the holding material is pressed. It can also be seen that the nonwoven fabric is more easily stretched if the nonwoven fabric is perforated.

(Test 2)
A polyethylene film or polyethylene nonwoven fabric having a length in the longitudinal direction of 530 mm and a length in the width direction of 144 mm was prepared, and as shown in Table 2, a circular or elliptical opening was formed by drilling to form a protective film. The openings in each protective film have the same dimensions, and are formed in three rows in the width direction as shown in FIG. 5 while changing the number in the longitudinal direction. In addition, the major axis of the elliptical opening was set along the longitudinal direction.

And said protective film was joined to the single side | surface of the alumina fiber base material of the basis weight 1200g / m < ² > by longitudinal direction length 530mm and width direction length 144mm, and it was set as the holding material. In addition, as for joining, only Example 15 applied the adhesive by spraying, and the others were hot presses.

11 Metal casing 12 Catalyst carrier 13 Holding material 45 Base material 50, 50A Protective film 60 Opening

Claims (7)

A holding material used in a catalytic converter comprising a catalyst carrier, a metal casing that houses the catalyst carrier, and a holding material that is wound around the catalyst carrier and interposed in a gap between the catalyst carrier and the metal casing. And
A holding material for a catalytic converter, wherein a protective film having an opening is bonded to a surface of an inorganic fiber substrate on a metal casing side.   The holding material for a catalytic converter according to claim 1, wherein the opening ratio in the protective film is 10 to 45%.   The holding material for a catalytic converter according to claim 1 or 2, wherein the shape of the opening is a circle or an ellipse.   The length of the minimum part of an opening is 5 mm or more, The holding | maintenance material for catalytic converters in any one of Claims 1-3 characterized by the above-mentioned.   The holding material for a catalytic converter according to any one of claims 1 to 4, wherein an interval between adjacent openings is 3 mm or more. The basis weight of the protective film in which the opening is formed is 20 g / m ² or less. The holding material for a catalytic converter according to claim 1,   The organic component of the whole holding material is 3 mass% or less of the total amount of the holding material, The holding material for catalytic converters according to any one of claims 1 to 6.

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